There has been proposed an inkjet printer including a detachable main tank, a sub-tank configured to store therein ink supplied from the installed main tank, and an image recording unit configured to record an image by discharging the ink stored in the sub-tank. Since internal spaces of the main tank and the sub-tank of the inkjet printer open to the atmosphere, the ink is moved by a water head pressure so that liquid levels of the main tank and the sub-tank are to be the same height. When a remaining amount of the ink detected by a remaining amount detection sensor becomes below a threshold value, the inkjet printer displays on a display that the main tank is to be replaced.